Ancuta P, Fahmi H, Pons J F, Le Blay K, Chaby R
Endotoxin Group, URA-1116 of the National Centre for Scientific Research, University of Paris-Sud, Orsay, France.
Immunology. 1997 Oct;92(2):259-66. doi: 10.1046/j.1365-2567.1997.00338.x.
We studied the pathways of macrophage response to lipopolysaccharide (LPS). When mouse macrophages pre-exposed to LPS were restimulated with this agent, reduced tumour necrosis factor-alpha (TNF-alpha) responses (desensitization/endotoxin tolerance) were accompanied by increased (priming) nitric oxide (NO) responses. Priming was also inducible with recombinant interferon-beta (IFN-beta). The requirement of TNF-alpha biosynthesis in the LPS-induced priming was also suggested by the observation that both anti-TNF-alpha serum and pentoxifylline inhibited this effect. However, addition of mouse recombinant TNF-alpha (mrTNF-alpha) did not enhance the priming induced by LPS or IFN-beta, and preincubation with mrTNF-alpha alone, or in association with other cytokines produced by macrophages (interleukin-1 beta, interleukin-6, or leukaemia inhibitory factor), did not induce a priming effect. We found however, that pentoxifylline, which blocked the priming, also decreased the level of membrane-bound TNF-alpha. Furthermore, exposure to compound BB-3103 (a metalloproteinase inhibitor that blocks the processing of membrane-bound TNF-alpha yielding to the secreted cytokine) enhanced the priming effect, the expression of membrane TNF-alpha and the specific binding of LPS. These observations suggest that the membrane form of TNF-alpha is involved in the interaction of LPS with a receptor required for LPS-induced priming.
我们研究了巨噬细胞对脂多糖(LPS)的反应途径。当预先暴露于LPS的小鼠巨噬细胞再次受到该试剂刺激时,肿瘤坏死因子-α(TNF-α)反应降低(脱敏/内毒素耐受),同时一氧化氮(NO)反应增强(启动)。重组干扰素-β(IFN-β)也可诱导启动。抗TNF-α血清和己酮可可碱均抑制这种效应,这一观察结果也提示了LPS诱导启动过程中TNF-α生物合成的必要性。然而,添加小鼠重组TNF-α(mrTNF-α)并不能增强LPS或IFN-β诱导的启动,单独用mrTNF-α预孵育,或与巨噬细胞产生的其他细胞因子(白细胞介素-1β、白细胞介素-6或白血病抑制因子)联合预孵育,均未诱导出启动效应。然而,我们发现,阻断启动的己酮可可碱也降低了膜结合型TNF-α的水平。此外,暴露于化合物BB-3103(一种金属蛋白酶抑制剂,可阻断膜结合型TNF-α加工生成分泌型细胞因子)可增强启动效应、膜TNF-α的表达以及LPS的特异性结合。这些观察结果表明,TNF-α的膜形式参与了LPS与LPS诱导启动所需受体的相互作用。